The present disclosure relates generally to the field of occupant classification systems and occupant position detection systems. More specifically, the disclosure relates to resistive and capacitive sensing systems and sensing methods for a vehicle seat.
One of the problems with current weight based occupant classification systems in vehicles is their inability to capture the entire occupant weight due to offloading. Offloading is the occurrence of alternate paths of occupant weight transfer. For example, offloading occurs when the occupant rests their feet close to the base of the seat removing the weight of their legs from the seat, transferring leg weight directly to the floor of the vehicle instead of the weight sensing devices.
There or many other forms of occupant offloading including but not limited to head and arm offloading while the occupant is leaning against the center console and leaning against the vehicle door. The complete weight of the head, arms, and legs is not transferred through the weight sensors if the occupant is leaning forward.
Vehicle manufacturers are aware that weight based systems do not capture offloading and therefore do not always capture the full weight of the occupant. This inaccuracy is one input in determining occupant classification threshold strategies.
There are occupant classification systems that measure the weight of a person utilizing various technologies like strain gauges, capacitive mats, hall effect sensors, and pressure sensing materials. The current designs also do not capture both the occupant weight and position. Current occupant position detection systems utilize capacitive mat technology, which has several limitations and is not used as a single system with occupant classification systems. The current occupant classification designs also are only used for passenger seats.